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<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        let a="name"
        a="mm"
        console.log(a);
        const b="ddd"
        console.log(b);
        // b="ccc"常量不可被修改
        const arr=[1,2,3,4,"hhh"]
        console.log(arr)
        arr[0]=100;
        console.log(arr)
    </script>
</body>
</html>